JP2004-35115A discloses a conveyor-belt wear detector in which a wear-detecting layer having a color different from that of an elastic layer of a belt body is embedded in a belt body, the colored wear-detecting layer being exposed with wear of the elastic layer to allow the wear to be found.
As another measure for detecting wear, thickness of a conveyor belt is periodically determined by an ultrasonic-wave thickness meter to find wear while the conveyor belt stops.
In DE19525326C1 a number of transponders are embedded at different depths from the surface in a belt. Destruction or dropout of any one of the transponders with wear of the belt is detected by an antenna comprising a transmission coil and a sensor coil to allow wear of the belt to be found.
However, in the detector of JP2004-35115A and the ultrasonic wave thickness meter, it is very difficult to determine the amount of the wear automatically. Wear has to be determined visually by a person while the conveyor belt stops, so that its efficiency is poor.
In DE19525326C1, a number of transponders have to be embedded over a broad range to make the device itself larger, which requires a high cost.